Abstract

Background

Rheumatoid arthritis (RA) disease activity is often measured using the 28 joint Disease Activity Score (DAS28). We aimed to identify and independently verify subgroups of people with RA that may be discordant with respect to self-reported and objective disease state, with potentially different clinical needs.

Five, 4 and 4 latent classes were found respectively in ERAN, BSRBR TNF-inhibitor and non-biologic cohorts. The proportion of people assigned with >80% probability into latent classes were 76%, 58% and 72% in ERAN, the TNF-inhibitor and non-biologic cohorts respectively. The latent classes displayed either concordance between measures indicative of mild, moderate or severe disease activity; discordantly worse patient-reported measures despite less markedly elevated inflammation; or discordantly less severe patient-reported measures despite elevated inflammation. Latent classes with discordantly worse patient-reported measures represented 12%, 40% and 21% of the ERAN, TNF-inhibitor and non-biologic cohorts respectively, contained more females, and showed worse function. In those latent classes with worse scores at baseline, DAS28 and function improved over 1 year (p<0.001 for all comparisons), and scores differed less at follow up than at baseline.

Discussion

Discordant latent classes can be identified in people with RA, and these findings are robust across 3 cohorts with varying disease duration and activity. These findings could be utilised to identify a sizeable subgroup of people with RA that might gain added benefit from pain management strategies.

Item Type:

Article

Keywords:

Rheumatoid arthritis – Pain – Inflammation – Latent class analysis

Schools/Departments:

University of Nottingham, UK > Faculty of Science > School of Psychology